Energy question of the week: are large hydroelectric power stations genuinely good for the environment?

After decades of planning, Belo Monte - the third largest hydroelectric power station in the world, will now be constructed in the Amazonas region of northern Brazil. When the Brazilian Institute of Environment and Renewable Natural Resources, IBAMA, approved the plan in early February, it was met with vociferous criticism from environmental conservationists and spokespersons for indigenous groups. So just how green are gigantic hydroelectric power stations really?

This is an exceptionally tough question to answer. In a densely populated region like Europe, the construction of a dam the size of a city such as Hamburg would soon be equated with an environmental catastrophe. Thousands of people would need to be relocated, vast areas of forest destroyed, innumerable species of plant and animal life would be threatened with extinction, massive quantities of climate-damaging methane would be released and, at a local level, permanent changes in climate might occur. None of these arguments are incorrect. Even countries such as Brazil, which have an enormous amount of land available, are fully aware of this. "The implications for our environment do exist, but they have been weighed, analysed a great deal and mitigated," said Carlos Minc, the Brazilian Minister for the Environment.

The overflow ramp on the world’s second-largest power station, Itaipu, on the border between Brazil and Paraguay, with a capacity of 14,000 megawatts generated from 20 turbines. Credit: Jan Oliver Löfken. Jan Oliver.

A large amount of 'clean' power

Belo Monte has a planned capacity of 11,200 megawatts, meaning that only two other power stations on Earth are more powerful: the Three Gorges Dam in China and the Itaipu power station on the border between Brazil and Paraguay. This power generation capacity is comparable to that of up to eight large nuclear power stations or 16 medium-sized coal-fired power stations – this tends to put the counter-arguments into perspective. This is particularly true in times of climate change, when all parties would like to generate their electricity with zero carbon dioxide emissions. After all, once they have been built, large hydroelectric power stations generate electricity for decades with very little impact on the climate. Moreover, this power is incredibly inexpensive to produce, as the example of Itaipu demonstrates. Here, each kilowatt-hour of power is generated at a cost of roughly four eurocents. "When compared to large coal-fired or nuclear power stations, large hydroelectric power stations always emerge with compelling climate-related and environmental credentials,” says Cicero Bley, Coordinator of the Brazilian Observatory for Renewable Energy, with conviction. Given that almost 12 percent of the world's fresh water flows through the rivers of Brazil, this energy expert is convinced that it makes perfect sense to use this resource. This is a commonly held view in Brazil, questioned only by a minority.

It follows that, given the growing hunger for electrical power in countries such as Brazil and China, there is a tendency to downplay the implications of any large-scale hydroelectric power station. Moreover, the company that ultimately wins the current invitation to tender for construction of the Belo-Monte project and goes on to build the dam will be obliged to invest more than 1.5 billion Real – about 500 million Euro – in environmental projects in the area surrounding the power station on the Xingu river.

Downpipes on the Itaipu power station on the border between Brazil and Paraguay. Credit: Jan Oliver Löfken.

Plenty of criticism from conservationists and from indigenous peoples

Justified criticism from those directly affected follows: "We oppose dams on the Xingu and will fight to protect our river," announced Megaron Tuxucumarrae, a leader of the Kayapo tribe that inhabits the Xingu region, according to the non-governmental organisation Amazon Watch. Belo Monte must not be allowed to destroy the ecosystem and diversity of native species. Furthermore, up to 40,000 people would need to be relocated from the flooded area. In addition - and this is one of the strongest arguments being put forward by the conservationists - the power station may be unable to generate electricity for up to four months a year as a consequence of inadequate volumes of water. This does not justify the massive investment required, which is estimated to be in the region of 12.3 to 17.5 billion USD.

Environmental conservation in the region, or large volumes of climate-friendly electrical power with zero carbon dioxide emissions? It is not possible for large hydroelectric power stations to achieve both these objectives at the same time. If construction work proceeds, every possible effort must be made to mitigate the environmental implications. Given the anticipated profits, there would certainly be enough money to accomplish this. However, there are reasonable doubts as to whether monies would be well invested in this course of action. Torn between these arguments, it is not possible to provide a clear answer to this conundrum and this is regrettable. Nonetheless, we are interested in knowing your views on this topic.

The DLR Energy question of the week in 'The future of energy' Year of Science

The Federal Ministry of Education and Research (BMBF) has given the Year of Science 2010 the motto 'The future of energy'. For this reason the science journalist Jan Oliver Löfken will this year answer a question on the subject of energy in his blog each week. Do you have a question about how our energy supply might look in the future? Or do you want to know, for example, how a wave power plant works and how it can efficiently generate electricity? Then send us your question by email. Science journalist Jan Oliver Löfken will investigate the answers and publish them each week in this blog.

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Energy journalist Jan Oliver Löfken writes among other things, for the Technologie Review, Wissenschaft aktuell, Tagesspiegel, Berliner Zeitung and P.M. Magazin on issues involving energy research and industry. For DLR, he answered the Energy question of the week during the Year of Energy 2010.
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